text: People poured out of offices in the city centre after an evacuation warning sounded. At least one person has died.
  Donetsk has been surrounded for several weeks by Ukrainian forces battling pro-Russian rebels.
  The convoy of at least 260 lorries carrying Russian aid has now halted, after moving towards the border.
  There is continuing confusion over the final destination. On Thursday afternoon, the lorries had got to within a few miles of the border, where they had parked in a field, reports the BBC's Steve Rosenberg, who is following the convoy.
  We followed the convoy for about nine hours, having left Voronezh before dawn. The convoy turned off the main highway - the M04 -  on to a smaller road to the border. All the lorries are now parked here in a field.
  We asked one commander to show us the contents of the lorries. He selected one, and it contained sleeping bags. But it was just one of at least 260 lorries. I cannot say accurately what the contents of the others are. The lorries will wait here until the convoy is given orders - but there is no indication when that will be.
  I spoke to one driver. He was very anti-American and asked why the United States was trying to take Ukraine away from Russia.
  The key question now is what Russia does next. If it takes the convoy across the border, it will be seen by the Ukrainian authorities as a major provocation.
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  Russia has dismissed as absurd claims that its convoy is a pretext to send military supplies to the rebels.
  But Ukraine has said the Russian convoy must be inspected by international monitors before it can be let in.
  Andriy Lysenko, a spokesman for Ukraine's National Security and Defence Council, said that if this did not happen, "movement of the convoy will be blocked with all the forces available".
  Meanwhile, the situation is reported to be desperate in the rebel-held city of Luhansk, where civilians have been short of water, food and electricity for more than a week. Phone lines are also down as shelling continues.
  Artillery fire could be heard all around Donetsk on Thursday, with the authorities urging people to stay off the streets.
  Two shopping centres were reportedly hit.
  It was unclear who had fired the shells.
  One city resident,  Valentina Smirnova, told Associated Press as she cleared up rubble: "My son left and now I am staying with my daughter. I don't know what to do afterwards. Where should I run to after that?"
  A senior International Red Cross (ICRC) official, Laurent Corbaz, is flying to the Ukrainian capital Kiev and then on to Moscow to discuss the Russian aid initiative.
  The ICRC tweeted that it had made initial contact with the Russian convoy but that "many practical details are still to be clarified".
  Ukraine is also sending a humanitarian aid convoy to the east.
  Some 75 lorries with 800 tonnes of aid left Kiev, Kharkiv and Dnipropetrovsk for Luhansk on Thursday morning, the presidential website said.
  Some 2,086 people have been killed since the conflict in the east began in mid-April, more than half of them in the past two weeks, the UN says.
  The violence began when pro-Russian rebels seized government buildings and tried to declare independence.
  The military launched an operation to retake the east, and stepped up its activities in June.
  Meanwhile, Russian President Vladimir Putin has been visiting Crimea, where he announced he had approved a defence ministry plan to set up a "Russian military taskforce".
  However, Mr Putin also struck a conciliatory tone, saying: "We must calmly, with dignity and effectively, build up our country, not fence it off from the outside world."
  He added: "We do not intend, like some people, to dash around the world with a razor blade and wave that blade around. But everyone should understand that we also have such things in our arsenal."
  Russia annexed the territory from Ukraine in March, in a move that drew international condemnation.
target: Heavy shelling has hit the rebel-held Ukrainian city of Donetsk, amid a continuing row over a controversial Russian aid convoy.